Perhaps that is already happening, with a select few manufacturers. But consider that many marketplace sellers are third parties (e.g. an electronics shop). Or other manufacturers with different costs (many factors affect this... location, workforce..). What happens with these?

I do wonder if Amazon are making any kind of profit on these items. With their long term strategy they can very well afford to make a loss just to undercut the competition and put their products out there, make a name.